1. Field of the Invention
The present invention relates to growth of films of material, and, more particularly, to the growth of diamond-type films and related devices.
2. Description of the Related Art
Diamond is a useful industrial material, combining the desirable properties of electrical non-conductance along with high thermal conductance. These properties make diamond a good candidate material for isolating circuit levels in multilevel circuit boards.
A method for forming a continuous diamond film is disclosed in co-pending application, Ser. No. 231,750 filed Aug. 12, 1988 now U.S. Pat. No. 5,006,203. In the disclosed method, diamond film is grown in a multistep process: the first step grows a film under conditions yielding good film coverage of a diamondlike layer; this diamondlike layer is then etched with atomic hydrogen to preferentially remove graphitic-bonded material, resulting in a primarily diamond-bonded surface; the final step grows a film under conditions yielding a high quality diamond layer. The diamondlike layer provides a high nucleation density for diamond growth, resulting in a high quality diamond layer.
However, also needed in order to use diamond as an interlevel insulator, is a method of forming a patterned diamond film containing vias for interconnecting the circuit levels. Because of the chemical inertness of diamond it is difficult to etch the required vias.
Known methods of patterned diamond film growth rely upon destruction of previously formed diamond nucleation sites. Discrete diamond particles have been formed in a patterned array on a silicon substrate by use of a silicon dioxide shadow mask. This is accomplished by forming diamond nucleation sites over the entire surface of the silicon-dioxide-masked silicon substrate. The entire substrate is then irradiated with an oblique Ar ion beam which selectively reduces the number of nucleation sites. This process is limited to growing particles on one edge of the silicon dioxide site. See Ma et al, Selective nucleation and growth of diamond particles by plasma-assisted chemical vapor deposition, 55 (11) Appl. Phys. Lett. 1071,1989.